Tropical coastlines featuring mangrove, seagrass, and coral habitats are of immense ecological and socio-economic importance, supporting biodiversity, carbon storage, coastal protection, fisheries, and tourism. However, climate change, coastal development, and low water quality increasingly threaten these interconnected coastal ecosystems, particularly in semi-enclosed bays where the impacts of these stressors are often amplified. Yet, physicochemical conditions are rarely assessed at sufficient temporal resolution (i.e., diel and seasonal variation) and time-integrated pollution monitoring is rarely performed. Here, we used a multi-disciplinary approach to assess >20 abiotic parameters characterizing two mangrove- and seagrass-dominated inland bays and two nearby coral reefs in Curaçao (southern Caribbean) during the cool, dry season and warm, wet season. This was combined with time-integrated pollution monitoring using bioindicators to assess nutrients and trace metal pollution (inland bays only), and passive samplers and bioassays to assess organic chemical pollution (all four sites) during the wet season. This approach revealed a previously undocumented extent of strong diel and seasonal environmental variability in Curaçao's inland bays, with temperature, pH, and dissolved oxygen frequently reaching values predicted under moderate-to-severe future climate scenarios as outlined by the IPCC (2021). In addition, the inland bays had greater nutrient concentrations (especially ammonium) and potential ecotoxicological risks than the nearby reefs during the wet season due to run-off and anthropogenic activities. These findings emphasize the importance of high-resolution monitoring to understand risks across appropriate temporal scales and establish an environmental baseline against which future monitoring can be benchmarked. Moreover, our study provides a robust water quality assessment framework that can be used by natural resource managers to monitor reef-associated habitats and conserve their high ecological and socio-economic value. Overall, our work highlights the urgent need to improve monitoring, water quality, and protection of these valuable reef-associated habitats.

Increasing temperature beyond a species’ optimum is a major threat to insect biodiversity, particularly in rapidly warming regions such as the Arctic. For cold-adapted pollinators, high temperatures can disrupt physiology and ecosystem services, threatening pollinator populations and plant reproduction. In bumblebees, increased temperature disrupts the physiology of the indirect flight muscles. However, these muscles, which generate the bee’s charismatic buzz, also facilitate key non-flight behaviours including communication, defence, and buzz-pollination, where temperature effects remain unexplored. Here, we assess the thermal performance of non-flight muscle function across 15 Arctic bumblebee species by measuring thorax vibrations during defensive buzzing behaviour. Thorax acceleration is found to peak at an air temperature of 25 °C, declining after this peak as a potential strategy to prevent overheating. Conversely, vibration frequency continues to increase with temperature, and is better explained by thorax temperature than air temperature. Surprisingly, there are no differences in thermal response across species, castes, or temperature habitat specialisations, indicating that non-flight vibrations are similarly susceptible to unfavourable temperatures across bumblebee species. If such findings translate to non-flight buzzing in other contexts, such as buzz-pollination, changes in buzzes have the potential to disrupt key plant-pollinator interactions.

Bumblebees (genus Bombus) are key pollinators in many ecosystems, yet their foraging performance and pollination efficiency are highly sensitive to environmental conditions, particularly temperature. As global temperatures undergo rapid changes due to climate change, understanding how thermal variation affects bumblebee behavior, physiology, and biomechanics is crucial for predicting potential disruptions to pollination services. Bumblebees possess a unique ability among insects to generate internal heat and are regarded as cold-adapted specialists. However, this adaptation also makes them highly vulnerable to rising environmental temperatures. Using a combination of laboratory experiments and field observations with commercial bumblebees, this thesis explores the impact of environmental temperature on bumblebee foraging behavior, flight control, vision, and pollination performance. In Chapter I, we examine how temperature impacts commercial bumblebee colonies by surveying foraging activity in a field site using both radio frequency identification (RFID) tags and manual surveys. We measured colony activity (number of departures and arrivals) as well as bumblebee body temperature upon depature and arrival and monitored colony and environmental temperature. Our results showed that while Biobest workers began foraging at cooler temperatures and increased both their foraging duration and pollen collection as environmental temperature rose, Koppert colonies exhibited relatively stable foraging behavior across temperatures, with shorter trips and less temperature-dependent pollen collection. These findings highlight the need to consider breeder-specific traits when choosing colonies for crop pollination in different climates. In Chapter II, we used laboratory experiments to understand how environmental temperature affects bumblebee body temperature and thermoregulation during different behaviors (i.e., during resting, pre-flight, and post-flight). We measured head, thorax, and abdomen temperature. We found that the effect of environmental temperature on bumblebee body temperature differs across behavioral contexts and that bumblebees use a counter-current heat exchanger to thermoregulate during during/ after flight. In Chapter III, we aimed to understand how increasing temperatures and decreasing light availability affect bumblebee visual performance and flight control. We measured visual performance by recording electroretinogram responses of bumblebees at different temperatures and light intensities. Additionally, by recording bumblebees flying during periods of dim and bright light at different temperatures, we assessed components of flight control, including flight speed, straightness, and centering. Photoreceptor SNR peaked at intermediate temperatures, declining at both low and high extremes. We found that bumblebees increase their flight speed as temperature increases, but only in bright light and this is aided by the increase in visual performance. On the contrary, during periods of dim light and lower temperatures, bumblebees fly slower likely caused by decrase in the visual performance. In Chapter IV, we examined how temperature influences the foraging behavior (i.e., number of flowers visited and time spent on each flower) of bumblebees using buzz-pollinated Solanum rostratum plants. We also investigated the vibratory mechanics of buzz pollination—a process in which bees generate rapid thoracic vibrations to extract pollen from flowers with poricidal anthers. We found that bumblebee foraging activity is affected by temperature, with bumblebees decreasing the amount of time spent on each flower and  visiting more flowers per minute. This temperature-induced variation in behavior affected the reproductive outcome of the plants, with fewer fruits and seeds being produced by plants that were pollinated by bees at the higher temperature.  We also found that vibration frequency, amplitude, and pollen release efficiency are significantly affected by temperature. By integrating ecology, behavior, physiology, and biomechanics, this thesis provides novel insights into the thermal sensitivity of bumblebees and their pollination effectiveness. The results emphasize the vulnerability of bumblebee populations and pollination services in a changing climate, underscoring the need for conservation strategies that promote pollinator resilience.

Over the past decades, increasing environmental temperatures have been identified as one of the causes of major insect population declines and biodiversity loss. However, it is unclear how these rising temperatures affect endoheterothermic insects, like bumblebees, that have evolved thermoregulatory capacities to exploit cold and temperate habitats. To investigate this, we measured head, thoracic, and abdominal temperature of bumblebee (Bombus terrestris) workers across a range of temperatures (24 °C–32 °C) during three distinct behaviors. In resting bumblebees, the head, abdomen, and thorax conformed to the environmental temperature. In pre-flight bumblebees, the head and abdominal temperatures were elevated with respect to the environmental temperature, while the thoracic temperature was maintained, indicating a pre-flight muscle warming stage. In post-flight bumblebees, abdominal temperature increased at the same rate as environmental temperature, but the head and the thoracic temperature did not. By calculating the excess temperature ratio, we show that thermoregulation in bumblebees during flight is partially achieved by the active transfer of heat produced in the thorax to the abdomen, where it can more easily be dissipated. These results provide the first indication that the thermoregulatory abilities of bumblebees are plastic and behavior dependent. We also show that the flight speed and number of workers foraging increase with increasing temperature, suggesting that bees do not avoid flying at these temperatures despite its impact on behavioral performance.